Daughters first weekend drag racing!!
Hey, tell her she´s a cutie ;-)
Regarding the front drum: imo with a 904 you don´t have to worry about that. It´s not that the sprag can´t fail, but the drum is much smaller diameter and therefore the centrifugal force is much less than with a 727. As far as i know such catastrophic damage never happened with a 904.
Have fun!
Michael